In the related art, a method for forming a three-dimensional structure is known based on a model of a three-dimensional object, for example, generated by three-dimensional CAD software or the like.
As one method for forming a three-dimensional structure, a stacking method is known. In the stacking method, in general, after splitting the model of a three-dimensional object into a large number of two-dimensional cross-sectional layers, a three-dimensional structure is formed by sequentially stacking a cross-section member while sequentially forming the cross-section member corresponding to each two-dimensional cross-sectional layer.
By the stacking method, a three-dimensional structure can be formed immediately as long as there is a model of a three-dimensional structure to be formed, and since there is no need to make a die before forming, it is possible to quickly and inexpensively form a three-dimensional structure. In addition, since a three-dimensional structure is formed by stacking a cross-section member having a thin plate-shape one layer by one layer, for example, even in a case where the object has a complex internal structure, it is possible to form an integrally formed object without being divided into a plurality of parts.
As one such stacking method, a technology for forming a three-dimensional structure while hardening a powder with a binding liquid is known (for example, refer to PTL 1). In this technique, when each layer is formed, by discharging an ink containing a colorant to the location corresponding to the outer surface side of a three-dimensional structure, the three-dimensional structure is colored.
However, in the methods in the related art, it is difficult to reliably control the surface condition of the three-dimensional structure, and for example, it is substantially impossible to selectively use an appearance of a matte tone and an appearance of a gloss tone at a desired portion.